Apparatus and method for automated medical diagnostic tests

An automated analytical system for sequential-injection sample analysis, the automated analytical system comprising:

• (a) a multipositional stream-selection device;
• (b) a fluid-propulsion device, in fluid communication with the multipositional stream-selection device, for conveying a fluid to and from the multipositional stream-selection device;
• (c) a source of sample, in fluid communication with the multipositional stream-selection device;
• (d) a reagent reservoir containing a lyophilized or a concentrated reagent which, when dissolved in or diluted by a solvent, forms a reconstituted reagent that is capable of reacting with a component of the sample to form a reaction product detectable by the automated analytical system;
• (e) a source of solvent, in fluid communication with the multipositional stream-selection device, for dissolving or diluting the lyophilized or concentrated reagent;
• (f) a detector, in fluid communication with the multipositional stream-selection device, for generating a signal indicative of concentration of the component of the sample;
• and
• (g) a central processing unit, operatively connected to the multipositional stream-selection device, and constructed and arranged for automatic control of fluid flow between the multipositional stream-selection device, the sample source, the reservoir containing the lyophilized or concentrated reagent, the solvent source, and the detector;
• wherein the reagent reservoir includes a porous frit, to facilitate mixing of the solvent with the lyophilized or concentrated reagent, and to prevent residual solids from being drawn from the reagent reservoir with the reconstituted reagent.